A communication scheme (Device to Device, D2D) for performing direct communication between UEs without passing eNB in mobile communication systems is discussed. Such a communication scheme is specified in Long Term Evolution, Release 12 which is a telecommunications standard standardized by Third Generation Partnership Project (3GPP).
In D2D communication, a UE transmits data and control information by the use of a resource selected from a resource pool. A resource represents time and frequency which can be assigned when a UE transmits a control signal or data within a channel with a predetermined period and a frequency band which are specified in D2D communication. The resource pool includes a plurality of such resources.
In particular, for a UE (Out-of-coverage UE) located outside a cell provided by an eNB, a set of resource pools for data transmission and a set of resource pools for sidelink control are configured in advance in a UE. Note that these pre-configured sets of resource pools are installed in a UE, for example, at the time of factory shipments.
In the set of resource pools for data transmission, the resource pool described at a head of a list in which the sets of the resource pools are presented is used for both data transmission and reception, whereas other resource pools are used only for data reception. Similarly, also in the set of resource pools for sidelink control, the resource pool described at a head of a list in which the sets of the resource pools are presented is used for both transmission and reception of sidelink control, whereas other resource pools are used only for sidelink control reception.
Examples of the related art include a Non Patent Literature (J. Schlienz et al. “Device to Device communication in LTE Whitepaper”, ROHDE&SCHWARZ).